The turbo will take as much oil you can give it. The bearings provide a flow restriction, once the oil passes the bearings it drips into the return tube then to the oil pan.

There are a few ways to test for turbo oil leaks. ( for all of this, keep flammable stuff away from open exhaust. )

To test for leaking turbo, remove it from the exhaust , block the oil feed and return tube then run engine. The turbo oil feed block off must take ~ 80 PSI without leaking.

Another way would be to remove turbo from exhaust, leave oil feed attached, extend the oil return with a piece of heater hose ( or similar ) then run the engine and look for oil leaking from the turbo.